How to load external modules/packages into blender python
For pip-installable dependencies (like PyPI or wheels), all you need to do is the following:


Locate your Blender's Python binary path, let's call it &lt;BPYTHON&gt; (in my case 2.80/python/bin/python3.7m at the Blender installation).
Run the following to enable pip operations in bpython:


&lt;BPYTHON&gt; -m ensurepip
&lt;BPYTHON&gt; -m pip install --upgrade pip



Now any time you want to install a package simply call pip from bpython:


&lt;BPYTHON&gt; -m pip install &lt;YOUR_PACKAGE&gt;  # no --user needed
&lt;BPYTHON&gt; -m pip install &lt;PATH/TO/WHEEL&gt;.whl  # also works with wheels as expected


As usual, you just have to install a package once and uninstalling works the analogous way.

Blender's Python has its own environment, so this procedure will install the dependencies there (in my case the 2.80/python folder). AFAIK this will work irrespectively of your OS, system's Python version and Blender location so I found this to be most convenient. You can encounter some issues if installing cython-related packages like tkinter but this can also be fixed as I did here.

Let me know if this works out!
Cheers,
Andres